1. Field of the Invention
This invention relates to ceiling fans. More particularly, this invention relates to vibration dampers for ceiling fans.
2. Description of the Background Art
Motor driven fans suspended from the ceiling were used extensively in homes in the United States to provide air circulation before the introduction and popularization of central cooling units.
When the energy crisis dawned in the 1970's, the cost of a kilowatt hour sky rocketed in price and consumers searched for ways to reduce their heating and cooling costs. It has been well established that properly circulated air will raise the overall thermal efficiency of the home air conditioning and cooling system and hence, reduce the cost of maintaining a home at a desired comfort level year round. Thus, ceiling fans were repopularized in the 1970's.
Mass produced, low cost ceiling fans have several disadvantages that must be tolerated in return for savings in energy. The lower cost fans are typically noisy and vibrate excessively and the blades visibly sway. The noise and vibration are largely caused by pulsating torques common to all single phase AC motors.
Ceiling fans typically comprise a plurality of fan blades which are rigidly connected to the rotor of an electric motor by means of fan blade brackets integrally formed with or threadably fastened to the blades. In some ceiling fans, the inner rotor rotates within the outer stator of the electric motor as exemplified in U.S. Pat. No. 1,935,314. In other types of ceiling fans, commonly known as "spinner" fans, the rotor constitutes the outer housing of the fan and rotates about the inner stator. U.S. Pat. Nos. 4,621,977 and 4,720,241 disclose such spinner-type fans.
Previous attempts to reduce the noise and vibration originally focused on placing elastomeric grommets about the threaded fasteners which innerconnect the fan blades to their respective fan blade brackets. Similar attempts have also focused on attaching all of the fan blade brackets to a mounting ring and then threadably securing the mounting ring to the rotor through the use of threaded fasteners positioned through elastomeric grommets. U.S. Pat. No. 4,511,310, the disclosure of which is hereby incorporated by reference herein, illustrates the latter embodiment. In both embodiments, the threaded fastener comprises a bolt having a shank portion greater in length than the thickness of the grommet such that the shank prevents compression of the grommet upon tightening of the bolt. Thus, the grommet is freely suspended between the head of the bolt and the rotor.
The use of elastomeric grommets between the fan blades and the fan blade brackets or between the rotor and a mounting ring to which the fan blades are rigidly connected, have both been favorably accepted in the industry. Notwithstanding, the fan blades may "wobble" since the resiliency provided by the freely suspended elastomeric grommets is essentially the same for torsional, axial, and radial forces.
Therefore, it is an object of this invention to provide an apparatus which overcomes the aforementioned inadequacies of the prior art devices and provides an improvement which is a significant contribution to the advancement of the ceiling fan vibration damper art.
Another object of this invention is to provide a vibration damper for ceiling and other fans which provides torsional damping to dampen the pulsating torque created by single phase electric motors.
Another object of this invention is to provide a vibration damper for ceiling and other fans for torsionally damping pulsating torques while minimizing radial and axial movements.
Another object of this invention is to provide a vibration damper for ceiling and other fans which may be easily incorporated in existing fan constructions during the manufacture thereof.
Another object of this invention is to provide a vibration damper for ceiling fans which may be easily retrofitted to existing fans upon removal of the fan blades and brackets.
Another object of this invention is to provide a vibration damper for ceiling and other fans which does not adversely effect the aesthetic appearance of the fan.
The foregoing has outlined some of the more pertinent objects of the invention. These objects should be construed to be merely illustrative of some of the more prominent features and applications of the intended invention. Many other beneficial results can be obtained by applying the disclosed invention in a different manner or modifying the invention within the scope of the disclosure. Accordingly, other objects and a fuller understanding of the invention may be had by referring to the summary of the invention and the detailed description of the preferred embodiment in addition to the scope of the invention defined by the claims taken in conjunction with the accompanying drawings.